Reproduction

Question 1

what are male gonads called?

Answer 1

testes

Question 2

where is sperm produced?

Answer 2

in the seminiferous tubules of the testes

Question 3

what are spermatogonia?

Answer 3

spermatogonia are located in the seminiferous tubules of the testes (where sperm is made).
spermatogonia arise from the epithelial tissue to become spermatocytes, spermatids and spermatozoa

Question 4

what do sertoli cells do?

Answer 4

they surround and nurture spermatocyte and spermatids

they are stimulated by FSH

Question 5

What do leydig cells do?

Answer 5

release testosterone when stimulated by LH

Question 6

What is the function of testosterone?

Answer 6

its the primary androgen (male sex hormone) and stimulates the germ cells to become sperm. its also responsible for secondary sex characteristics (pubic hair, enlargement of the larynx, growth of penis and seminal vesicles).
- it also helps with the closure of epiphyses of the long bones , ending growth in stature.

Question 7

what happens when a spermatid becomes a spermatozoon?

Answer 7

it loose its cytoplasm and form a head, mid piece and a tail

Question 8

what does the head contain?

Answer 8

nucleur material and acrosome (lysosome like enzymes which will penetrate the egg)

Question 9

what does the mid piece have?

Answer 9

lots of mitochondria to help provide energy for movement

Question 10

which piece enters the egg?

Answer 10

only the nucleur portion

Question 11

where does the spermatozoon go to mature?

Answer 11

epididymis!

Question 12

what happens to spermatozoa upon ejaculation?

Answer 12

propelled through the vas deferent into the urethra and out of the penis

Question 13

what is semen?

Answer 13

mixture of spermatozoa and fluid that leaves the penis

-its composed of fluid from the seminal vesicles, the prostate, and bulbourethral glands (cowpers glands)

Question 14

where do the spermatozoa become activated for fertilization?

Answer 14

in the vagina a process called capacitation occurs.

Question 15

when does oogenesis begin?

Answer 15

in the ovaries of the fetus . alll the eggs of the female are arrested as primary oocytes at birth.

Question 16

what happens at puberty?

Answer 16

FSH stimulate growth of granulosa cells around the primary oocyte. which will secrete viscous substance around the egg called zone pellucida. the structure @ this stage is the primary follicle.

Question 17

how does the secondary follicle form?

Answer 17

theca cells grow around the follicle . upon stimulation by LH, theca cells secrete androgen which is converted to estradiol (type of estrogen) by the granulosa cells in the presence of FSH and is secreted into the blood.
Estradiol will prepare uterine wall for pregnancy. the follicle grows and bulges from the ovary

Question 18

what happens just before ovulation?

Answer 18

estradiol levels rise rapidly, which cause a dramatic increase in LH secretion. this increase is called luteal surge

Question 19

what happens in the luteal surge?

Answer 19

the luteal surge results from a positive feedback loop of rising estrogen levels which results in increase LH levels , which increase estrogen. the luteal surge causes the follicle to Burst , releasing the egg (now a secondary oocyte).

Question 20

what happens to the released egg (secondary oocyte)?

Answer 20

egg is swept into the Fallopian tube or oviduct by fimbriae. the remaining part of the follicle becomes the corpus luteum

Question 21

what does the corpus luteum do?

Answer 21

it secretes estradiol and progestrone throughout pregnancy or in the case of no pregnancy: for about 2 weeks until it degrades into corpus albicans

Question 22

how often does this cycle repeat itself?

Answer 22

28 days ( called the menstrual cycle)

Question 23

what are the three phases of the menstrual cycle?

Answer 23

1) the follicular phase- begins with development of the follicle and ends @ ovulation
2) luteal phase: begins with ovulation and ends with degradation of the Corpus luteum
3) flow : shedding of the uterus lining lasts ~5 days

Question 24

Where does fertilization take place?

Answer 24

in the Fallopian tubes. the enzymes in the acrosome are released upon contact with the egg.
cell membranes of the sperm and the oocyte fuse upon contact and sperm nucleus enters the cytoplasm of the oocyte. this entry will cause cortical reaction, which prevents other sperms from fertilizing the same egg.
now the oocyte goes through another division ( second meiotic division) to become an ovum and it releases a second polar body

Question 25

when does fertilization occur?

Answer 25

when the nuclei of the ovum and the sperm fuse to form a zygote.

Question 26

cleavage

Answer 26

cleavage starts while the zygote is still in the Fallopian tube. the zygote foes thru many cycles of mitosis - when its 8 or more cells : its called a morula. (at this stage they are totipotent)- they can express any genes ( so any of these 8 cells can make its own individual).

Question 27

what happens to the morula?

Answer 27

the cells continue to divide to form a hollow ball filled with fluid : called a blastocyst.

Question 28

what does the blastocyst do?

Answer 28

it will lodge onto the uterus in a process called implantation on about 5-7 days after ovulation.

Question 29

what kind of cells is the blastocyst made of?

Answer 29

embryonic stem cells: which can develop into MOST of the types of cells in the human body

Question 30

what happens at implantation?

Answer 30

female is said to be pregnant

- upon implantation, egg secretes HCG ( human chorionic gonadotropin)

Question 31

what is the function of human chorionic gonadotropin that’s secreted by the impacted egg?

Answer 31

it prevents degeneration of corpus luteum and maintains the secretion of estrogen and progesterone.
HCG in the blood and urine is the first sign of pregnancy.

Question 32

what does the placenta do?

Answer 32

so the placenta forms from the tissue of the egg and from the tissue of the mom and takes over the job of hormone secretion.
- it reaches full development by end of the first trimester
and begins secreting its own estrogen and progesterone

Question 33

what is determination?

Answer 33

• process where a cell becomes committed to a specialize developmental path.
• become determined to give rise to a specialized tissue early on.
• fate is determined earlier on, but that same cell docent usually differentiate into specialized tissue until much later at the end of the developmental process.

Question 34

What is gastrulation?

Answer 34

where a gastrula is formed. ( cells begin to move about the embryo for the first time) - this is after the second week after fertilization

Question 35

During gastrulation which 3 germ layers are formed?

Answer 35

1) ectoderm
2) mesoderm
3) endoderm

Question 36

Fate of the ectoderm…

Answer 36

epidermis of the skin, nervous system, sense organs

Question 37

fate of mesoderm

Answer 37

skeleton, muscles, blood vessels, heart, blood, gonads, kidneys, dermis of the skin

Question 38

fate of endoderm

Answer 38

lining of digestive and respiratory tracts, liver, pancreas, thymus , thyroid

Question 39

in the third week the gastrula develops into what?

Answer 39

neurala in a process called neurulation. this is where notochord induces the overlaying ectoderm to thicken and form the neural plate.
the notochord will disintegrate, while the neural tube will form from the neural plate.
the neural tube will become the spinal cord, brain, and most of the nervous system.

Question 40

what is apoptosis regulated by?

Answer 40

protein activity ! not transcription or at the translation process!
the proteins involved in apoptosis are present but they are inactive in a normal healthy cell.